1. Field of The Invention.
This invention relates generally to the field of automotive transmissions and more particularly to devices for preventing contamination of transmission fluid by lubricating oils from automotive engines such as diesel or gasoline engines.
2. Brief Description of The Prior Art.
Complex mechanical systems such as automotive power trains typically employ several different kinds of fluids, e.g., fuels, lubricating oils, hydraulic fluids, transmission fluids, coolants, etc. As a general rule such fluids are contained in a specific sub-system or location and any contact between such fluids is usually regarded as an undesirable contamination of one fluid by another. Consequently, many devices and systems have been developed to prevent such fluid contamination.
Art known to the applicant which is generally concerned with collecting and/or redirecting fluids, e.g., oil, hydraulic fluids, coolants, etc. leaked from mechanical devices can be summarized as follows:
U.S. Pat. No. 2,618,351 teaches an oil sump pan which is attached to the lower surface of a crankcase. The lower surface of the sump pan has a corrugated surface to increase the oil cooling surface area. The pan has a simple outlet hole for the oil collected in the sump pan.
U.S. Pat. No. 4,499,969 teaches an oil salvage block assembly which collects lubricating oil at a point beneath the travel of a reciprocally moving block and transfers the oil, via a flexible tube, to a collection point.
U.S. Pat. No. 2,304,255 teaches an oil pan baffle device which directs oil down from a release passage to a point beneath an oil reservoir level (as opposed to being directed into the oil reservoir) and thereby decreasing undesirable foaming in the reservoir which would otherwise occur if the incoming oil stream were merely splashed into the top surface of the oil reservoir.
U.S. Pat. No. 2,438,245 teaches a system for returning leakage oil to a main fluid supply. The oil is collected in a sump and transferred to a collection tank whose liquid level operates a float valve. When the float valve is open a venturi or jet educator sucks the oil from a storage tank and returns it to a circulating oil system.
U.S. Pat. No. 4,187,817 discloses a system to modulate fuel flow to each cylinder of an internal combustion engine based upon, in part, increased air pressure within the engine's intake manifold in order to achieve more effective fuel/air ratios. The system is based upon diaphragm operation of a fuel flow modulating valve which is responsive to engine intake manifold pressure which, in turn, is detected via an air line connecting a diaphragm operator with the intake manifold. The system also has a drain line for returning any fuel which may leak into the diaphragm operator due to leakage in a seal.
U.S. Pat. No. 4,271,860 teaches a valve system wherein any fluid leakage around seals between a sleeve and a stem and between the sleeve and housing flows downward into an underlying chamber and then through drain openings to the atmosphere.
U.S. Pat. No. 4,300,589 teaches a hydraulic brake fluid drainage collection device for the wheel cylinder of drum brakes. The device is comprised of a catch basin mounted under the cylinder and a tube which extends from the bottom of the catch basin to a point outside of the system.
U.S. Pat. No. 4,389,984 teaches a device for supplying turbocharger impeller bearings with a coolant, e.g., crankcase lubricating oil. The device includes a valve seat which is closed during engine operation by a valve extending from the downstream side of the piston in order to return any coolant leaking downstream of the piston to the oil crankcase.
All the references cited above involve the use of fluid catching and/or fluid diverting means, but none is specifically adapted to the task of collecting oil leaking from a crankshaft seal in the gear train housing which usually separates an automotive engine from its transmission. This is an ongoing problem because crankshaft seals in such gear train housings eventually wear down and/or they wear a depression in the crankshaft which rotates in such seals. In either case the seal starts to leak oil from the crankcase side of the housing to the transmission side of said housing. Under present procedures, such leaks are usually dealt with by replacing the seals and this in turn usually involves pulling the engine and/or the transmission.
Leakage of this type usually starts to occur before the engine and/or transmission otherwise needs to be overhauled, repaired or replaced. For example, the crankshaft seals in many diesel powered buses often start to leak after about 80,000 miles. If engine oil is allowed to continue to leak into the transmission side of the housing and hence into the transmission fluid, the transmission soon begins to suffer in efficiency (and in terms of increased mechanical wear) and begins to "slip", that is to rotate without delivering power to the drive wheels. Typically, initial leaks of this type are remedied by use of so-called "speedy sleeves" which are in effect sleeves which are placed on the crankshaft. That is to say that they are mounted, as collars, around the crankshaft. So mounted, they rotate in a new oversized seal; that is to say they rotate in a new seal whose center hole is larger than that of the original seal in order to accommodate the increased diameter of the speedy-sleeve mounted on the crankshaft. In time, however, say at 110,000 miles, these speedy sleeves also begin to leak. At this point the engine is often overhauled and the seals are replaced. Replacing worn seals with either speedy sleeves or with new seals involves economic costs far beyond the costs of the seals themselves. By far the largest costs are those associated with the skilled labor needed to pull the engine and/or transmission and to replace the seals. For example, in the case of diesel powered buses the whole engine/transmission package must be pulled in order to replace a worn seal. This operation may take two to three man/days of a skilled mechanic's time.
This invention seeks to provide methods and apparatus whereby the expensive operation of pulling the engine/transmission package to replace a worn seal can be delayed without causing damage to the transmission. That is to say this invention is particularly concerned with saving the economic cost of the first pulling of the engine/transmission package (e.g., at 80,000 miles in the case of a diesel engine/transmission package for a bus) so that the unit can continue to operate effectively until such time as a second pulling of the engine/transmission package (e.g., at an additional 30,000 miles, that is to say at 110,000 miles) is normally scheduled and at a point in the engine's life when replacements and repairs, other than replacement of seals, also may be required as part of the overall maintenance schedule for the vehicle.